In recent years, with the improvement of controllability of mobile electronic devices and the development of the electronic technology, the touch screen technology has a wide range of applications in electronic devices such as a mobile phone, a tablet, a laptop computer and the like. The touch screen technology develops in different technical directions such as resistive, capacitive, electromagnetic directions and the like, and capacitive touch screens have become the mainstream products due to low cost and excellent user experience.
With rapid growth of the capacitive touch screens, people have increasing requirements for Electro-Static Discharge (ESD) performance of touch products. ESD may cause deterioration of performance of devices in a touch screen or breakdown of the devices which results in permanent failure, such as open or short circuit in the touch screen.
A conventional touch substrate comprises a touch area for touch detection and a black matrix pattern surrounding the touch area. Touch electrodes and dummy electrodes located in gaps between adjacent touch electrodes are formed on a touch substrate, and the dummy electrodes function to adjust mutual capacitance and match refractive index. The black matrix pattern is generally made of carbon balls. Generally, the black matrix pattern has good insulation performance, but after multiple high-temperature manufacturing processes, the black matrix pattern has reduced resistivity and decreased insulating property. In this way, when electrostatic charges of a device or a human body contact electrode blocks on the black matrix pattern, large discharge current is instantaneously formed between different electrode blocks, which results in breakdown of the black matrix pattern and causes open or short circuit between the electrode blocks, thereby resulting in deterioration of the touch performance or permanent failure of corresponding areas. After massive data validation, it is found that breakdown between different electrode blocks usually occurs between a touch electrode and adjacent dummy electrodes.